It is critical when using ActiveX that all references be closed when they are no longer needed. When left open, these references create pointers from LabVIEW into the ActiveX application that neither program can properly deal with. The temporary solution should be to reboot.
If a ref cascades into another method or property, close it afterward it's last use. This includes the refs for Application, Workbook, Sheets, Sheet, Range, Cell1, Cell2, etc. If the ref does not leave a subvi, then close it in there.
You will know that all references are closed only when this problem goes away.
Michael Munroe
Certified LabVIEW Developer
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